Systematic Determination of Complex Reaction Mechanisms

斯坦福大学的约翰·罗斯得到了理论和计算化学项目的支持，以开发进一步确定复杂反应体系的反应路径和机制的方法。这项工作强调了测量次数少、精度可能有限的方法的必要性。将探索四种新方法。首先，将通过理论、模型反应计算和实验来检验脉冲微扰方法，以阐明反应路径中物种的因果连接性。将使用理论和计算来研究这种方法的一种变体，即延迟响应法，目的是提供关于反应路径中的化学物种数量、速率系数和反应机理的信息。遗传算法方法将被用在一个模型系统上，以研究生物系统中的振荡化学反应可能由于规则的周期性扰动而进化的可能性，重点是外部效应引起的反应机制的进化变化。最后，对单分子反应中的记忆效应和振荡的反应机理和随机分析进行了研究。确定化学反应是如何发生的是包括生物化学在内的所有化学领域的一个重要目标。在过去的近一百年里，人们一直在探索这一任务，方法是确定存在的化学物种，分别研究整个反应系统中各种基本化学反应的速率，然后猜测反应机理，即从反应到再现观测结果的产物的基本反应步骤的适当组合。对于复杂的化学反应体系，这是一项艰巨且往往有争议的任务，因为许多不同的提出的反应机理经常与现有数据相吻合。本项目将开展的研究从另一个角度探讨化学反应机理问题的解决，其结果可能对体外乃至最终在体内确定复杂的化学和生化系统的机理产生重大影响。

John Ross of Stanford University is supported by the Theoretical and Computational Chemistry Program to develop further approaches to the determination of reaction pathways and mechanisms of complex reaction systems. The effort emphasizes the need for methods with small numbers of measurements, possibly of limited accuracy. Four new methods will be explored. In the first, a pulse perturbation approach will be examined using theory, model reaction calculations, and experiments, in order to elucidate the causal connectivities of species in the reaction pathways. A variant of this approach, a delayed response method, will be studied using theory and calculations with the goal of providing information on the number of chemical species in the reaction pathways, on rate coefficients, and on the reaction mechanism. Genetic algorithm methods will be used on a model system to study the possibility that oscillatory chemical reactions may have evolved in biological systems as a result of regular periodic perturbations, focusing on evolutionary changes in a reaction mechanism due to external effects. Finally, the reaction mechanism and stochastic analysis of memory effects and oscillations in single-molecule reactions will be investigated. Establishing how chemical reactions occur is an important goal in all fields of chemistry, including biological chemistry. This task has been approached, for nearly the last hundred years, by determining the chemical species present, studying separately the rates of various elementary chemical reactions in the entire reaction system, and then guessing the reaction mechanism, which is the proper combination of elementary reaction steps that lead from reactions to products that reproduce observations. For complex chemical reaction systems, this is an arduous and often controversial task, since many different proposed reaction mechanisms frequently fit the available data. The research that will be carried out in this project approaches the solution of chemical reaction mechanism problems from an alternative viewpoint, and the outcomes may have substantial impact on the determination of the mechanisms of complex chemical and biochemical systems in vitro, and ultimately in vivo.